BSc Data Science focuses on statistics, big data analytics, machine learning and related aspects which make you understand the problems/phenomena with respect to a set of real world data whereas BSc IT revolves around the processing and management of information in a systematic way through the subjects technical communication skills , data structure using c language, content management system, etc.
So you can have a rough idea about the two courses but which one is better is something only you can decide as you will know better which subject interests you more.